Update documentation for collecting Boolean string mBeans

[lgh2]

What does this PR do?

Updates the documentation for collecting Boolean string-type mBeans.

Motivation

Customer request

Preview

https://docs-staging.datadoghq.com/laura.hampton/update-syntax-for-bool-mbeans/integrations/faq/i-have-a-matching-bean-for-my-jmx-integration-but-nothing-on-collect/

Additional Notes

---

Reviewer checklist

• [ ] Review the changed files.
• [ ] Review the URLs listed in the Preview section.
• [ ] Check images for PII
• [ ] Review any mentions of "Contact Datadog support" for internal support documentation.